e70fd44f9b
19146: cpu/esp32: fix and improve UART initialization r=benpicco a=gschorcht ### Contribution description This PR fixes issue #19138 that was introduced with PR #19100. It contains the following changes to fix the problems and to improve the UART initialization: - If `LOG_LEVEL` is greater or equal 4, such as in `tests/log_printfnoformat`, the ESP-IDF config function called for the GPIO pins of the UART will output the configuration with `printf` before the `_GLOBAL_REENT` structure is initialized. This causes a crash during system startup. Therefore the initialization by `syscalls_init` must be called by `earlier in the startup procedure. - Since PR #19100 it is possible to define: - other pins for `UART_DEV(0)` than the default pins - different `UART_DEV(0)` pins for the bootloader and RIOT To allow correct reinitialization of the UART pins used by the bootloader as well as their usage for other purposes, the pin usage for the default UART0 pins and the UART pinsused by the bootloader are reset to `_GPIO`. This is done in `uart_system_init` which has to be called earlier in the startup procedure. - To avoid garbage on reconfiguring the UART console pins, e.g. in initialization of the `arduino` module, pins that are already configured as UART pins must not be initialized. - To avoid a several msec long LOW pulse resulting in some garbage during the UART initialization, the TX line is set to HIGH and temporarily configured as a pull-up open-drain output before configuring it as a push-pull output. The PR requires a backport to 2023.1 ### Testing procedure The following tests should work with this PR: - [ ] `tests/log_color` - [ ] `tests/log_printfnoformat` - [ ] `tests/sys_arduino` ### Issues/PRs references Fixes #19138 Co-authored-by: Gunar Schorcht <gunar@schorcht.net>
The friendly Operating System for IoT!
RIOT is a real-time multi-threading operating system that supports a range of devices that are typically found in the Internet of Things (IoT): 8-bit, 16-bit and 32-bit microcontrollers.
RIOT is based on the following design principles: energy-efficiency, real-time capabilities, small memory footprint, modularity, and uniform API access, independent of the underlying hardware (this API offers partial POSIX compliance).
RIOT is developed by an international open source community which is independent of specific vendors (e.g. similarly to the Linux community). RIOT is licensed with LGPLv2.1, a copyleft license which fosters indirect business models around the free open-source software platform provided by RIOT, e.g. it is possible to link closed-source code with the LGPL code.
FEATURES
RIOT provides features including, but not limited to:
- a preemptive, tickless scheduler with priorities
- flexible memory management
- high resolution, long-term timers
- MTD abstraction layer
- File System integration
- support 200+ boards based on AVR, MSP430, ESP8266, ESP32, RISC-V, ARM7 and ARM Cortex-M
- the native port allows to run RIOT as-is on Linux and BSD. Multiple instances of RIOT running on a single machine can also be interconnected via a simple virtual Ethernet bridge or via a simulated IEEE 802.15.4 network (ZEP)
- IPv6
- 6LoWPAN (RFC4944, RFC6282, and RFC6775)
- UDP
- RPL (storing mode, P2P mode)
- CoAP
- OTA updates via SUIT
- MQTT
- USB (device mode)
- Display / Touchscreen support
- CCN-Lite
- LoRaWAN
- UWB
- Bluetooth (BLE) via NimBLE
GETTING RIOT
The most convenient way to get RIOT is to clone it via Git
$ git clone https://github.com/RIOT-OS/RIOT
this will ensure that you get all the newest features and bug fixes with the caveat of an ever changing work environment.
If you prefer things more stable, you can download the source code of one of our quarter annual releases via Github as ZIP file or tarball. You can also checkout a release in a cloned Git repository using
$ git pull --tags
$ git checkout <YYYY.MM>
For more details on our release cycle, check our documentation.
GETTING STARTED
- You want to start the RIOT? Just follow our quickstart guide or try this tutorial. For specific toolchain installation, follow instructions in the getting started page.
- The RIOT API itself can be built from the code using doxygen. The latest version of the documentation is uploaded daily to doc.riot-os.org.
FORUM
Do you have a question, want to discuss a new feature, or just want to present your latest project using RIOT? Come over to our forum and post to your hearts content.
CONTRIBUTE
To contribute something to RIOT, please refer to our contributing document.
MAILING LISTS
- RIOT commits: commits@riot-os.org
- Github notifications: notifications@riot-os.org
LICENSE
- Most of the code developed by the RIOT community is licensed under the GNU Lesser General Public License (LGPL) version 2.1 as published by the Free Software Foundation.
- Some external sources, especially files developed by SICS are published under a separate license.
All code files contain licensing information.
For more information, see the RIOT website: